[ReactiveX][RxSwift]비동기 작업을 스트림으로 만들기 - 네트워크 예제

	import UIKit
	import RxSwift
	import RxCocoa

	protocol HTTPBinAPI {
		func get(parameter: String) -> Observable<[String:String]>
	}

	class HTTPBinDefaultAPI: HTTPBinAPI {
		let url = "http://httpbin.org/"
		static let sharedAPI = HTTPBinDefaultAPI()

		func get(parameter: String) -> Observable<[String : String]> {
			let requestURL = NSURL(string: url + "get?" + parameter)!

			return Observable.create { observer -> Disposable in
				let s = NSURLSession.sharedSession().dataTaskWithURL(requestURL) {
					(data, response, error) in
					if let error = error {
						observer.onError(error)
					}
					guard let
						data = data,
						json = try? NSJSONSerialization.JSONObjectWithData(data, options: []),
						args = json["args"] as? [String:String]
						else {
							observer.onError(NSError(domain: "Error", code: 1, userInfo: nil))
							return
					}
					observer.onNext(args)
					observer.onComplete()
				}
				s.resume()
				return NopDisposable.instance
			}
		}
	}

	extension Dictionary where Key:StringLiteralConvertible, Value: StringLiteralConvertible {
		func toParameterString() -> String {
			guard let _self = (self as? AnyObject) as? Dictionary<String, String> else {
				return ""
			}
			if _self.count < 10 {
				return (1..._self.count+1).map { "\($0)=\($0)" }.joinWithSeparator("&")
			}
			return (1..._self.count).map { "\($0)=\($0)" }.joinWithSeparator("&")
		}
	}

	class ViewController: UIViewController {
		var label: UILabel!
		var disposeBag = DisposeBag()
		let backgroundScheduler = SerialDispatchQueueScheduler(globalConcurrentQueueQOS: .Background)

		override func viewDidLoad() {
			super.viewDidLoad()

			let btn1 = UIButton(frame: CGRectMake(100,100,100,100))
			btn1.backgroundColor = .redColor()
			self.view.addSubview(btn1)

			label = UILabel(frame: CGRectMake(100, 200, 300, 100))
			label.backgroundColor = .whiteColor()
			label.font = UIFont.systemFontOfSize(20)
			self.view.addSubview(label)

			btn1
				.rx_tap
				.subscribeOn(MainScheduler.instance)		// 1
				.map { [String:String]() }		// 2
				.doOnNext { [unowned self] _ in
					UIApplication.sharedApplication().networkActivityIndicatorVisible = true
					self.label.text = "Loading..."
				}		// 3
				.observeOn(backgroundScheduler)		// 4
				.flatMapLatest { p in
					HTTPBinDefaultAPI.sharedAPI.get(p.toParameterString()).retry(2)
						.observeOn(MainScheduler.instance)
						.doOnNext { [unowned self] p in
							self.label.text = "Done"
					}
				}		// 5
				.observeOn(MainScheduler.instance)		// 6
				.subscribe { [unowned self] s in
					UIApplication.sharedApplication().networkActivityIndicatorVisible = false
					guard let e = s.element else {
						self.label.text = ""
						return
					}
					self.label.text = e.description
				}		// 7
				.addDisposableTo(disposeBag)
		}
	}

	.flatMapLatest { p in
		HTTPBinDefaultAPI.sharedAPI.get(p.toParameterString()).retry(2)
			.observeOn(MainScheduler.instance)
			.doOnNext { [unowned self] p in
				self.label.text = p.description
		}
	}
	.flatMapLatest { p in
		HTTPBinDefaultAPI.sharedAPI.get(p.toParameterString()).retry(2)
			.observeOn(MainScheduler.instance)
			.doOnNext { [unowned self] p in
				self.label.text = p.description
		}
	}